Lathe-bed



3 Sheets-Sheet"1;

(No Model.)

S. W. PUTNAM.

LATHE BED.

No. 291,398. Patented Jan. 1, 1884.

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(No Model.) 3 Sheena-Sheet 2.

S. W. PUTNAM.

' LATHE BED.

No. 291,398. Y Patentediam. 1,1884.

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LATHEVBBD. No. 291,398. vPatentedJem.l,1884,.

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SALMON W. PUTNAM, OF FITGHBURG, MASSACHUSETTS.

.LATHE-BED.

SPECIFICATION forming par@ of Letters recent naaeiee, dated January 1, 1884.

Application filed July 2l, 1583.

To L7/Z whom t `may concern:

Be it knownthat, SALMON W. PUTNAM, of Fitchburg, in the county of W'orcester, State of Massachusetts, lhave invented a new and useful Improvement in Lathe-Beds, of which the following isa full, clear,`and exactV description, reference being had to the accompanying drawings, Mmaking a part of this specication, in which- Figure l isa perspective view of a lathebed with my improvements attached. Fig. 2 is a longitudinal vertical section. sh owing the central rib or truss. Fig. 3 is a cross-section on the line w of Fig. 1. Fig. 4 is A a section through y yo'f Fig. 1. Fig. 5 is a rear elevation of the lathe-bed.

My improvements relate to beds of lathes for turning purposes; and they consist in the combination of devices hereinafter explained and claimed. y l

To enable othersskilled in the art to make anduse my invention, I will proceed to describe the exact manner in which I have carried it out.

In the drawings, A represents the bed propA er, and longitudinally through'the center of which I seourelthe rib-truss or backbone A',

for the purposeof giving rigidity to the table and obviating deiiection, particularly when the bed has to be made long.

It is well known by those skilled in the art that in all lathes the front of the carriage is much heavier than the rear side, and that also the weight of the cut,77 when the machine is at work, falls mostly on the front side of the carriage, and the action of these unequalized weights combines to cause the carriage to wear,

settle, and get out of true7 much more rapidly on the front way or track of the lathe than upon the `rear one, and this excessive wear is hastened by the prevailing practice of making both the front and rear ways of a like angle, orsimilar.` To overcomethis difficulty, and to offset this uneven wear, is one of the essential objects of my present invention. To remedy this great defect in lathes `and to retard and offset this uneven wear, I make the front way or track,`B, wider and at a more obtuse angle thanlthe rear one, B', as shown in Fig. 3 in cross-section. The amount of vari- No model.)

ance to be made between the two ways must be governed by the size and requirements 'of the work. On the average size lathe I make the variance about twenty per cent., more or less.

All lathe-beds are made with their tops more or less in projection, as shown at a a in Fig.

3; but the distribution of metal at these points is such as to resist very imperfectly the shocks and strains brought to bear thereon when theV and pinion have hitherto supported the racks` gear and pinion by a stud and collar project,- ing from the inside of the feed-plate, thus leavo The feed-table of lathes operated by rack 7' ing the rack-pinion immediately Linder the rack, and where the greatest strain and wear come, and the farthest from the source of support, which is an element of weakness, and frequently causes very bad work. Another purpose of my present invention is to remedy this vdefect by supporting the rack-pinion D and gear in a yoke, E, having an arm-bearing, e, exten ding to the rear side of the rack D', thereby giving a double outside end support tothe rack-gear and pinion, which greatly increases their durability and firmness.

In lathes constructed with the actuatingscrew on the rear side ofthe bed the operating of the carriage-nut on the screw is performed by the operator reaching over the lathe and taking hold of a handle affixed to the eccentric plate of the said nut. This operation was very inconvenient and annoying, and to avoid this difficulty of having to reach across the lathe to operate the carriage-nut, I pass a rod, F, through the carriage from front to rear, and connect the eccentric plate G of the nut with the gears, as shown in Figs. 3 and 5. Other devices-such as cams, eccentric links, &c.- might be used in the place of the gears to con- IOC neet the rod and nut without departing from the spirit of my invention. Iprefer to employ the gear. Ahand-nut, f, is appliedto the rod on the front of the carriage, through the Inedium of which the back screw-nut, g, may be opened or closed conveniently from the front of the carriage, thus avoiding all occasion for reaching across the lathe to operate the carriage-nut. By the introduction of 4the crossrod F to operate the back nut, I am enabled to make connection with the feed-table on the front side of the lathe, and there affix a safetystop, b, by which it becomes impossible for the operator,through carelessness or otherwise,to engage at the same time the actuatingscrew onthe rear side of the lathe or apply the powerfeed to the rack and pinion in feed -table on the front of the lathe, thus doing away with the possibility of injuring or breaking the lathe. To make this point more clear, I will say that in lathes of like construction the feed for turning is obtained through a rod connected with the feed-table, and imparting motion to the carriage by engaging with the rack-gear on the opposite side .from the hand-feed. On the other hand, the motion of the carriage for screw-cutting is obtained through the actuating-screw. Both of these motions are positive, independent, and at different velocities of speed, and, as hitherto constructed, were liable to have the "power-feed in the feed-table and the actuating-screw engaged at the same time, with the usual result-broken gear. To prevent the possibility of such an accident, I introduce the safety-stop b. The gears for opferating the back nut on screw are so proportioned'. that it requires a little less than one revolution of the hand-knob to open and close the eccentric nut. The hand-nut has a hub passing into the carriage and on the under side of the carriage, directly under the hub, is a hole, c, extending well up into the hub. The stop-pin b is connected with the yoke E, that carries the rack-gear and pinion. When the rack-pinion is raised into the rack or disengaged therefrom,the upper end of the stop-pin is caused to enter the hole o or recede from it. In the former position the eccentric nut is locked by the pin and cannot be thrown into gear, and the carriage is operated through the rack and pinion; but when in the latter position the nut can be closed and the carriage is operated by the screW,While the rack and pinion are disengaged and are locked out. It is evident from this construction that either the screw or the rack-pinion may be in gear, but only one at the same time.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is'

l. In a lathe-bed, the front way or track, B, made wider or at a more obtuse angle than the rear track, B, in combination with the track B and the carriage, substantially as and for the purpose set forth.

2. The improvement in a lathe-bed,the rigid transverse ribs C, the longitudinal rib A', and the proj ectionsac, whereby the bed is stiifened and tremor is avoided, substantially as and for the purpose set forth. v V

3. In a lathe-bed, the rib A', secured longitudinally through the center of the table, substantially as and for the purpose set forth.

4. The rack-pinion D and gear, in combina tion with the carriage and the yoke E, armbearing e, and rack D, constructed to operate substantially as and for the purpose set forth.

5. rIhe rod F and gear, in combination with the eccentric plate Gandscrew-nut g, whereby the nut may be opened or closed from the front side of the carriage, substantially as and for the purpose set forth.

6. The rod F, provided with the hub b', perforated at c, in combination with the yoke E, provided with the stop-pin b, substantially as and for the purpose set forth.

SALMON W. PUTNAM.

Witnesses:

WILLIAM II. WHITNEY, GEORGE II. CARTER. 

